With numbers like that involved, it's no secret the operation of the ACA's insurance exchanges -- sometimes called marketplaces -- is critical to the law's success. With numbers so large, it's also been a monumental task for the Obama administration and the states to get the exchanges off the ground.

The exchanges will offer online marketplaces where individuals and small business employees can shop for various health plans, picking one that best suits them. Think of it as Kayak for health insurance.

Before that happens, the Department of Health and Human Services (HHS) must build the technological infrastructure to allow the government to determine eligibility and let individuals shop for plans, certify health insurers to sell on the exchanges, and educate consumers who are unaware of what the law offers, all while battling legal and political hurdles.

The exchanges will be open to individuals making between 100% and 400% of the federal poverty level who aren't offered health coverage through their employer, but who still need to meet the ACA's requirement that all individuals be covered by health insurance. They will receive financial help in the form of premium tax credits to help offset the cost of buying coverage.

Small businesses -- defined as those having 50 employees or less -- will also be allowed to shop on the exchanges for coverage for their employees.

States were given the option of building and operating their own exchanges or letting the federal government do so for them. A total of 27 states opted for a federally run exchange -- leaving the federal government to do a great deal of the work on its own. Many of those states are in the politically conservative Deep South and Midwest and have tried to turn their back on the 2010 health law.

Meanwhile, 16 states and the District of Columbia will build and operate their own exchanges, while another seven will partner with the feds in some way to run the exchanges. For example, New Mexico and Utah will run the exchange for small businesses and leave the individual marketplace up to the federal government. Our interactive map shows you which states are doing what.

Will the Exchanges Be Ready?

The Obama administration has said it is hopeful the exchanges will be operational on Oct. 1 when open enrollment for 2014 starts.

Several factors "suggest a potential for challenges going forward," the report stated. "And while the missed interim deadlines may not affect implementation, additional missed deadlines closer to the start of enrollment could do so."

However, "That report also felt unsatisfying in not giving us a really crystal clear vision of -- despite these issues -- do we think that states are on track or not on track to be operational on Oct. 1," Caroline Pearson, vice president at the Washington consulting firm Avalere Health, said. "We're hearing a lot of reassurances from the administration. Until you see functional demos of IT systems, it's really difficult for me or anyone on the outside to speculate."

Political opponents of the ACA have openly expressed doubt the Obama administration will be ready for open enrollment this fall.

"On a number of occasions, I've requested that they share with us the contingency plan of what to do if the exchanges aren't ready in time," Rep. Mike Burgess, MD (R-Texas), told MedPage Today in a statement. "They have steadfastly refused. The GAO report underscores the need for contingency planning to start immediately."

Supporters have continued to express confidence, reminding others there are several months before the Oct. 1 open enrollment begins.

"As the president has said, there will be bumps in the road, but we will get there," Rep. Jim McDermott, MD (D-Wash.) said in a statement. "Rather than scaring people, let's focus on the real work needed to make sure that this reform continues to help the millions of Americans it's intended to benefit."

Will Consumers Buy into Plans?

Meanwhile, there is still much ground to be made up in public outreach. Many who are unaware of or confused by the ACA could miss the chance to gain coverage starting in 2014.

Furthermore, about half of those polled said they don't have enough information to understand how it will impact them or their families, a figure that gets worse in uninsured and low-income families, for whom the law will have its biggest impact.

"We know that there have been some fundamental misunderstandings and lack of public awareness about what's going on," Jenny Sullivan, director of the group's best practices institute, told MedPage Today in a phone interview.

Enroll America and others like it are crafting massive outreach plans that are soon to launch if they haven't already. Efforts will include paid advertising to reach the masses as well as volunteer and community outreach from places such as churches and barber shops, Sullivan said. But work will vary from region to region.

"We know that every state, and every community is different, so different messages will work better in different places," she said. "We really need to make sure people know how to apply, know that it's a quick and easy process, and encourage as many folks as possible to apply."

CMS is providing $54 million in funding for exchange "navigators," workers who will provide unbiased information to consumers about health insurance, the ACA's exchanges, and public programs like Medicaid and the Children's Health Insurance Program.

Jean Abraham, PhD, professor at the University of Minnesota's School of Public Health in Minneapolis, said providers must also be aware of where these newly covered patients seek care.

"Our recent evidence is somewhat limited," Abraham told MedPage Today in a video interview. "Ultimately though, it's going to take providers as well as health plans to really educate the newly insured about what their options are for where they're going to seek care."

Pearson said hospitals are better positioned to do this and have already been making outreach efforts.

"Physicians are in a tricky spot because they're likely to get a lot of questions from their patients about what this means for them, but they haven't been to date the main targets of some of the education campaigns," Pearson told MedPage Today in a phone interview. "How well positioned they will be to help them is unclear at this point."

Will There Be Enough Plans?

Another unknown will be what plans are wanting to operate on the exchanges and how many will be available.

In California for example, Aetna and Cigna have decided not to participate despite large interest from other insurers, said Everette James, JD, MBA, director of the University of Pittsburgh's Health Policy Institute.

"It's really going to vary by state in terms of what options are available for consumers," James told MedPage Today in a video interview.

Some states have struggled with being able to offer plans on their individual and small business exchanges.

For example, Pearson said Mississippi, New Hampshire, and Iowa only have one plan expressing interest to sell on those states' exchanges. Some state's small business exchange options have also had sparse interest -- like Washington state, which only received one bid for its exchange.

The ACA does allow health insurers to offer plans in only certain parts of the state, an option that may dominate in lower-population states, Pearson said.

Another area of great variation is which benefits the plans will cover. While HHS has defined bare minimums in 10 categories all plans must cover -- so called "essential health benefits" -- states can require more than those minimums to operate on its exchanges, and plans can choose to go beyond that as well.

"Within those categories, there's still significant flexibility," Cheryl Smith, of Deloitte Consulting in Salt Lake City, said. "There's really a spectrum from state to state."

As with the course of any major healthcare entitlement rollout, few expect a perfectly smooth process, and obviously several questions remain.

"Something will be ready. Something will be rolled out October 1," Smith told MedPage Today. "It's going to be 'Hang onto your hats.' It's going to be a bumpy ride for the first 1 or maybe 2 years.

"In the course of this bumpy ride, we're starting to figure out things that work and things that don't work."

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